A control device of the general type to which this invention relates is disclosed in U.S. Pat. No. 4,574,651. Such a device has a control stick comprising an inner stick part which is fixed to a housing and which projects beyond a hand supporting surface on that housing, and an outer stick part which is connected end-to-end with the inner stick part and is swingable relative to it. The stick is embraced by an operator's hand, the heel of which rests on the supporting surface with at least the little finger curled around the inner stick part.
It is evident that any cavity in the stick parts of such a control device must be relatively small. Heretofore it has been considered impossible to build into such a cavity both a biasing means for urging the outer stick part to a neutral position and a device for producing electrical signals in response to movements of the outer stick part away from its neutral position. A control device of this type disclosed in U.S. Pat. No. 4,531,080 comprised a gimballed transmission linkage, a portion of which was housed in the cavity in the stick and which transferred control movements to signal generators located outside of the stick parts and to stick biasing means located adjacent to the signal generators. This arrangement was not optimum for an aircraft installation because of its relatively heavy weight and the relatively large amount of space that it occupied. Especially where the movable stick part must be swingable about each of two mutually perpendicular axes, the rather complicated linkage and its gimbal mountings that was needed for transmitting the stick movements to the respective signal generators was necessarily expensive, and, even when made with care and precision, it offered possibilities for loose play and binding.